Electrode assembly for discharge tubes



Dec. 24, 1946. L, E E 2,413,006

ELECTRODE ASSEMBLY FOR DISCHARGE TUBES Filed Dec. 17, 1941 Patented Dec.24, 1946 stso'rn'ons ASSEMBLY FOR DISCHARGE TUBES Percy L. Spencer, WestNewton, Mass, assigncr,

by m'esne assignments, to Baytheon Manufacturing Company, a corporationof Delaware Application December 17, 1941, Serial No. 423,308

8 Claims.

Thi invention relates to an electrical space discharge device in whichthe dimensions of the device are reduced to relatively small values.This invention also relates to the method of constructing the same. v

In an electrical space discharge device employed in high frequencycircuits it has been found advantageous to employ electrodes ofrelatively small dimensions. Where such tubes are designed for highamplification it has been desirable that the electrodes be arrangedrelatively close together. In such a device the assembly of theelectrodes on a' mass production basis presents various difficultiesbecause of the relatively small size and close spacing thereof. Moreoversince such a spacing oi the electrodes in a high gain, high frequencydevice of the character described is relatively critical, the furtherdifliculty of achieving accurate spacing between the electrodes, so asto produce electrical space discharge device of uniform operatingcharacteristics, is encountered when using standard methods ofmanufacture and standard types of construction.

When devices of the character described are subjected to extreme shock,as for example when they are located in rapidly acceleratingbodies, astill further difficulty is encountered. Because of the relatively mallsize of theelements and the necessity for close spacing thereof,-it hasproven diflicult to construct them sturdily or to assemble them in arelatively shock-proof construction.

t is of course obvious that While I have mentioned diflicultiesencountered in the manufacture and in the structure of high frequency,high gain electrical space discharge devices ofrelatively smalldimensions, these difiiculties are also present to a greater or lesserdegree in all types of electrical space discharge devices havingrelatively small dimensions.

An object of this invention is to provide a novel method of constructingand a novel arra'ngement of the electrode assembly whereby theelectrodes may be easily and quickly assembled and thereafter handled asan integral unit, this novel method and arrangement being adapted formass production.

Another object of this invention is to provide a novel method forconstruction and a novel arrangement of the electrode assembly wherebythe electrodes are automatically accurately spaced from each other.Despite the r elatively small dimensions of the" elements included inthe electrical assembly it is feasible to employ the or- 2 dinaryoperatorin manufacturing in accordance with this invention. No unusualskill is necessary to assure accuracy in the spacing of the electrodes.g V y A furtheri mportant objector the present invention is to provide amethod of construction and a novel arrangement of the electrode assemblywhereby said assembly is capable of withstanding relatively severeshocks without damage thereto.

Other" objects and advantages of this invention willbecome apparent andthe foregoing ob- J'ects will be best understood from the iollqwindescription of an exemplification thereof, reference-being had to theaccompanying drawing wherein: W I

Fig. 1 is an enlarged cross-sectional new of a tube embodying myinvention, said new being taken along line l i of Fig. 2 h

Fig. 2 is enlarged cross se'ctional'vie'w taken along line 2-2 of Fig.1; V

Fig. 313 an enlarged exploded view or the ele merits illustrated inFigs. 1 and'Z; the glass enve'lope and lead-in wires beingomittd; and

Fig. 4 is an enlarged perspective View of part of the electrode assemblyillustrated in" the prior figures," the anjodesb'eing omitted'and'thelead-in wires and-eathode-supporting spring being shown fragmentarily.

The electrode space" discharge device illustrated is a tube I having anenvelope 2 of som suitablematerial such as glass. 7

A directly heated filamentary cathode 3' is formed in the shapeofan'inverted V; It is suspended in theassembly from its apex 4, the freeends 5 thereof being connected as will bedescribed hereinafter. i

When assembled with the other electrodes the cathode is arranged so that'it is substantially flat and lies in a lane substantially parallel tothe planes in whichthe other electrodes lie.

The grid 6 is formed in two sections l and 3; each of said sectionsconsisting of a pair of P- shaped frames 9' of any suitable materialsuch as nickel. having the edges of i a fine wire mesh It arrangedtherebetweeh along; the closed portions of the P, as illustrated in Fig.3, and welded thereto and to each other. H

, In order to arrangethe grid so that it may be interposed between thecathode and anode I prefer to upset each of the sections 1 and 8 toforth therein relatively shallowv pans I! and I2 respectively. Thesepans H and l- 2 are then arrange'dopposite each other to form an openingl3 therebtween in which the cathodefi is arranged. To provide means forfastening the sections 7 and 8 together, flanges M are formed onopposite ends of each of the U-shaped pans H and i2. These flanges arethereafter welded together to thereby form a unitary grid electrode. Thelegs of the P-shaped frames 9 are thereby arranged against each other toform a tab l6 by which the grid 6 may be connected to its lead-in.

The grid 6 is substantially flat and when arranged in the assembly liesin a plane substantially parallel with the planes in which the otherelectrodes lie.

In order to separate the electrodes I prefer to provide insulatingmembers I1, l8, and I9, said members being substantially flat and ofpredetermined thickness. These members may be made of any suitableinsulating material, such as,

for example, mica. The insulating spacer member |9 may be a singlespacer or, as shown, a plurality of spacers which when joined have thedesired thickness, spacers I! and I8 together being preferably as thickas spacer l9. These members serve not only to insulate the electrodesfrom each other but also to provide accurate spacing thereof, theaccuracy of the spacing depending solely on the accuracy with which theinsulating spacing members are made. Since. however, accurate control ofthe thickness of such spacers is readily feasible in standardmanufacturing processes, this offers no difilculty.

In order to permit the electronic discharge to pass unimpeded directlyfrom the cathode to the anode I prefer to provide openings 20, 2|, and22 in insulating spacer members l1, I8, and I8 respectively. Theinsulating spacer members is and I8 are arranged adjacent and abuttinggrid 6. In order that these spacers may be interlocked with the grid so2,8 to prevent relative movement thereof the openings 2| and 22 are madeof such dimensions so that the pans H and I2 of the grid 6 fit snuglywithin the openings 2| and 22, so the vertical portions 23 of spacers 8and I9 abut the flanges 4.

It will therefore be seen that the grids and the insulating spacermembers l8 and H) are thereby interlocked so as to prevent relativemovement thereof in a vertical plane when said elements are arranged asshown in Fig. 1.

Spacer I! is especially designed so as to provide a convenient means forfastening the free ends 5 of the cathode 3. For this purpose the spacer|1 is preferably longer than the other spacers so that the lowerhorizontal portion24 thereof extends below the other spacers when theelectrode assembly is completed, as can best be seen in Fig. 4.

The free ends 5 of the cathode 3 are preferably secured as by welding tometal straps 25, which straps may be arranged on horizontal portion 24of spacer II. To secure the straps in position I prefer to providevertical slots 26 in the horizontal portion 24, said slots being spacedand extending into opening 20.

The. straps 25 formed from a strip of a suitable metal, such as nickel,each have one end 21 thereof doubled over the horizontal portion 24adjacent the slots 26 so that a portion of each strap lies within itscorresponding slot. These straps are bent tightly around the horizontalportion 24 and the ends 2'! of each of these straps are welded to themain portion thereof, thereby fixing the straps in position. The freeends 5.

bly between the spacers 8 and I9, are bent over to the straps 25 andwelded thereto.

Upon assembly when the cathode 3 is arranged within the grid opening I 3the upper horizontal portions 28 and the lower horizontal portions 29 ofthe insulating spacer members l8 and I9 are immediately adjacent thecathode and the lower portion 29 of l8 abuts the same. These horizontalportions help to position the cathode within the grid opening I 3.

The anode 3D is preferably made of a pair of flat plates 3| upset toform channels 32 which are arranged opposite each other to provide anopening 33 therebetween within which opening the various elements arearranged.

Flanges 34 on either side of the channel 32 are provided, said flanges34 being welded together to secure the plates together and thereby formthe integral anode 30.

In order to prevent relative movement between the insulating spacermembers and. the plates 3| of the anode, the horizontal portions 28 and28 of insulating spacer members l8 and Hi and the horizontal portions 24and 35 of insulating spacer member l which project above and belowplates 3| are extended horizontally so as to form shoulders 36 betweenwhich the anode plates 3| are held.

As will be seen the plates 3| of the anode prevent the elements formingthe electrode assembly from spreading in a horizontal plane, while theshoulders 36 which-interlock the spacers and the anode preventdisplacement in a vertical plane. Since spacers 8 and I9 are alsointerlocked with the grid 6, the grid too is secured against suchdisplacement of these shoulders.

To further insure a sturdy shock-proof structure the upper horizontalportions 28 of the insulating spacer members l8 and 9 and the upperhorizontal portion 35 of spacer I"! are preferably provided withhorizontal slots 3'! extending inwardly from the opposite ends of theseportions. A metallic band 38 is passed through said slots 21 around saidportions and the ends thereof are welded together.

To support the cathode 3, a spring member 39 is provided having at oneend thereof a hook 48 on which the apex 4 of the cathode 3 is hung, theopposite end of said spring member 38 being welded to the band 38.

In constructing an electrode assembly it is preferred that a ring 4% ofsuitable getter material be joined to the assembly by arranging saidring above the electrodes and securing it as by welding to a supportingmember 42 which may in turn be welded to the band 38.

Before the assembly begins the straps 25 are secured in' position on thelower horizontal portion 24 of spacer member i? and the grid sectionsare welded together. The anode plate 35 is arranged on a suitablesupporting surface and spacer I9, grid 6, spacer I8, spacer i1, and theupper anode plate 3| are placed thereon successively in the order named.The anode plates are welded together. The band 38, which preferably hasthe spring 38 welded thereto as well as the supporting member 24 whichin turn is welded to the getter ring 4|, is then arranged within slots3'! and the ends thereof welded together.

' The cathode 3 may. next be inserted in opening I3 of the grid and thefree ends. 5 thereof are bent.v

over towards the straps 25 and weldedthereto;

while the apexd is arrangedv over the hooklfl' and maintainedundertension by the spring 38.-

It will be seen that I have here provided an integral electrode assemblywhich can be handled as a unit. It will be further seen that theelectrodes and insulating spacer members of this unit which are arrangedto lie substantially flat are stacked in layers lying in substantiallyparallel planes.

Lead-in wires for the electrodes maybe provided as follows: lead-in 43may be connected to the flange 3d of the anode 3D; lead-ins 44 and 45welded to straps and lead-in 46 to tab iii of the grid.

The assembly as herein above described is thereafter inserted within theglass envelope 2.

A press 41 is formed at the bottom of the envelope 2 and seals thelead-ins therein, thereby providing support for the electrode assembly.The electrodes are heated to drive off the occluded gases and the getterring 4! is flashed to release the getter material while the tube I isbeing evacuated through the tip 48. The tip 48 is thereafter sealed.

It may be pointed out that the electrode assembly is a unit and can behandled as such in mass production. Since the accuracy of spacing isdependent solely on the dimensions of the spacers and electrodes, highlyskilled operators are unnecessary despite the relatively smalldimensions of the elements. By the method and arrangement hereinabovedescribed I have been able to produce tubes of a very small size on amass production basis. For example, tubes of the type hereinbeforedescribed and made according to this method have been constructed on amass production basis, the outside overall dimensions of said tubesbeing .275 inch thick, .365 inch wide,

and 1 inches long.

This arrangement has proved so sturdy that during tests in which theassembly has been placed in several glass tubes successively and theglass broken away, the only parts damaged were the getter ring and thecathode. Tubes made in accordance with this invention have been placedin a centrifuge and the Weight thereof increased from a few ounces toabout one hundred pounds. Under these severe conditions, the tubesremained intact.

While I have described my invention in specific detail it is obviousthat these details may be considerably varied without departing from thespirit thereof. For example, the various steps may be performed in adifferent order. The tube may have additional grids and. anodes, thecathode may be indirectly heated, or it may be a cold cathode. The tubemay be a high vacuum or gas or vapor-filled type. The getter ring may beomitted. These are but a few of the variations that would be apparent toanyone skilled in the art upon reading the disclosure hereof. It isaccordingly desired that the appended claims be given a broadinterpretation commensurate with the scope of the invention within theart.

What is claimed is:

1. In an electrical space discharge device, an integral electrodeassembly arranged in layers and comprising a plurality of substantiallyflat electrodes and a plurality of substantially flat insulating spacermembers interposed therebetween, said insulating spacer members lying inplanes parallel to the planes in which said electrodes lie, a portion ofeach of said insulating spacer members projecting beyond the electrodes,and means cooperating with said projecting portions for preventingrelative movement of said spacer members.

2. An electrode assembly for an electrical space discharge devicecomprising a plurality of electrodes, each lying in a planesubstantially parallel to the planes in which the other electrodes lie,and a plurality of insulating spacer members interposed between the saidelectrodes and interlocked therewith, said insulating spacer memberslying in planes parallel to the planes in which said electrodes lie, aportion of each of said insulating spacer members projecting beyond theelectrodes, and means cooperating with said projecting portions forsecuring said insulating spacer members together.

3. An electrode assembly for electrical space discharge devicescomprising a plurality of electrodes, a plurality of insulating spacermembers of predetermined thickness interposed between said electrodes,said electrodes being separated by the thickness of said spacer members,said insulating spacer members and electrodes interlocking to therebyprevent relative movement along one plane and means for preventingmovement along a plane perpendicular to said first mentioned plane.

4. An electrode assembly for an electrical space discharge devicecomprising a cathode, a grid surrounding said cathode, said grid havinga substantially rectangular cross-section, a pair of flat insulatingplates placed on opposite sides of said grid, each of said insulatingplates having an opening of substantially the size and shape of thecorresponding side of said grid to receive said side of said gridtherein, each insulating plate having a total thickness greater than thedepth of the grid extending into said opening, and an anode plate membersupported in contact with the other side of each of said insulatingplates.

5. An electrode assembly for an electrical space discharge devicecomprising a cathode, a grid surrounding said cathode, said grid havinga substantially rectangular cross-section, a pair of flat insulatingplates placed on opposite sides of said grid, each of said insulatingplates having an opening of substantially the size and shape of thecorresponding side of said grid to receive said side of said gridtherein, said grid having a flange extending between said pair ofinsulating plates on opposite sides of said grid, each insulating platehaving a total thickness greater than the depth of the grid extendinginto said opening, an anode plate member supported in contact with theother side of each of said insulating plates, and means for clampingsaid insulating plates together to clamp said flange and retain saidgrid firmly in place.

6. An electrode assembly for an electrical space discharge devicecomprising a cathode, a grid surrounding said cathode, said grid havinga substantially rectangular cross-section, a pair of fiat insulatingplates placed on opposite sides of said grid, each of said insulatingplates having an opening of substantially the size and shape of thecorresponding side of said grid to receive said side of said gridtherein, said grid having a flange extending between said pair ofinsulating plates on opposite sides of said grid, each insulating platehaving a total thickness greater than the depth of the grid extendinginto said opening, an anode plate member surrounding said grid andsupported in contact with the other side of each of said insulatingplates, abutments on said insulating plates engaging said anode platemember to prevent longitudinal movement thereof, and means for clampingsaid insulating plates together.

7. An electrode assembly for an electrical space discharge devicecomprising a plurality of electrodes, each lying in a planesubstantially parallel to the plane in which the other electrodes lie,and a plurality of insulating spacer members interposed between the saidelectrodes and interlocked therewith, said insulating spacer memberslying in a plane parallel to the plane in which the electrodes lie, aportion of each of the outer insulating spacer members projecting beyondthe electrodes, and means cooperating with 10 said projecting portionsfor securing said insulating members together.

8. An electrode assembly for an electrical space PERCY L. SPENCER.

